Thread: new cat pooing on the floor! Help

First if all, she probably is being fussy and doesn't want to use the tray if it smells of the other cats. However, once they start messing outside their tray, even if it's only once or twice, it becomes a habit. So, you need to shut her in one room with a brand new litter tray and wait for her to use it. Once she is established using it then she should be OK but it looks as though she is going to have issues with your other cats using it and not sure how you can address that one really in a multi cat household.